1. Field of the Invention
This invention relates generally to the fields of semiconductor, photovoltaic, flat panel, or LCD-TFT device fabrication.
2. Background of the Invention
As manufacturing processes in the semiconductor, photovoltaic, flat panel and LCD-TFT industries continue to develop and evolve, different materials are constantly under evaluation for use in these processes. For instance, many different organometallic molecules (or “precursors”) are being proposed as metal sources for depositing metal, metal oxide, and metal nitride layers for semiconductor manufacture. Typically, these materials are used for depositing thin film layers on substrates. Depositions of these materials may be carried out by several methods, including: chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD), atomic layer deposition (ALD) or plasma enhanced atomic layer deposition (PEALD). These precursors need particular physical and thermal properties to be used in a given semiconductor manufacturing process. For example, the precursors need to have high volatility, reactivity, and thermal stability.
One type of film being deposited for manufacturing integrated circuits is tantalum nitride (TaN), which is generally formed by using a CVD process (or PECVD) with the precursor “PDMAT” (pentakis(dimethylamido) tantalum (V)=Ta(NMe2)5). Other known precursors for the deposition of tantalum nitride include “PDEAT” (pentakis(diethlyamino)tantalum), and “PEMAT” pentakis(N-methlyethylamino)tantalum. These precursors may be reacted with NH3 to produce a highly uniform films with low resistivity, which may be used as a barrier layer to prevent copper (Cu) metallization.
However, there are certain challenges associated with the use and supply of precursor materials. For instance, since the precursor is delivered to the deposition chamber in the gas phase, a precursor must have a sufficient vapor pressure to provide enough material for uniform deposition. However, most of the precursors for these films are solids at room temperature where they have low vapor pressures. This then requires the delivery temperature of the precursor to be higher than room temperature. For example with PDMAT, this temperature is often approximately 75° C. Thus, an important property of the precursor is the thermal stability of the precursor at this elevated temperature. If a precursor decomposes prior to deposition, the resulting films are often contaminated or non-uniform. In addition to this thermal stability, material compatibility is often an issue. A precursor must be compatible with the material that the chemical is delivered or stored in. In addition, the precursors are often delivered with a carrier gas such as argon (Ar) or nitrogen (N2) often at reduced pressures.
Consequently, there exists a need for methods and systems which decrease the possibility of precursor decomposition during storage prior to deposition.